Automatic carburetor deicing system



July 23, 1940.

Filed Jan. 8,v 1958 INVNTOR ATTORN t Patented Jul'y 23, 1940 v AUTOMATIC CARBURETOR DEICIN SYSTEM` Edmund c'. sulzman, Caldwell, N. J., assignor to Wright Aeronauticalv Corporation, a corporation of New York Application January 8, 1938, Serial No. 183,991 claims. (c1. 12s-122)' This invention relates to internal combustion aircraft engines and comprises particularly a combination of apparatus to afford air temperature control and automatic elimination of icing 5 in the induction system of the engine.

One of `the problems currently encountered in aircraft engine operation is the formation of ice in the induction system, particularly in the vicinity of the carburetor, which ice may o accumulate to constrict the induction system openings and produce other effects to the detriment of engine power output. This ice formation is known to occur under certain combinations of temperature and humidity in the atmosphere, and it is generally known that if the fuelair mixture after passing through the carburetor is maintained at a level of 35 F. or more, ice will not form anywhere in the inductionsystem. With modern supercharged engines it is desired 2@ to hold the intake temperatures as low as possible to attain greater volumetric eiiiciency in the engine. This does not interfere with the proper carburization since fuel sprayed into the entering air is thoroughly atomized by passage through the supercharger and, there -is a tem-l perature rise in the supercharger itself, soI that the charge entering the cylinders ls actually somewhat warmer than the air in the vicinity of the carburetor. If the humidity conditions are favorable, entering air temperatures may be very much lower than freezing or in the freezing zone without danger of ice formation. It is only during a certain critical range of temperature and humidity, as above indicated, that ice formation takes place. v

In the prior art, means have been 50 mation commences, to raise the temperature of 4 the air entering the system, to the elimination of the ice and to. the prevention of further ice formation while icing conditions persist in the atmosphere. A further object is to provide 55 means responsive to icing which will establish providedto indicate the presence of ice in-the induction air temperature control in the engine intake and will maintain this control until same 1s cut out by selective manipulation by the aircraft crew. I

Further objects lwill be apparent vin reading the annexed detailed description in connection with the drawing, in which Fig. 1 indicates an engine carburetor incorporating the several devices whichcomprise the invention, .and Fig. 2 is an elevation showing the devices associated with a conventional cowledin aircraft powe plant.

I have indicated the carburetor and the de'- vices of the invention partly in fulllines and partly in section, electrical connections` being. shown diagrammatically, for the sake of clarity, I0 represents an air intake scoop open to the -ambient air, directly connected with an air in as a means for warming air passing between the e 'Y engine cylinders so'that the air rearward of the cylinders is at elevated temperature.l This applies particularly in the case of. aircooled engines. In the duct II, I provide a portl I6 opened to the zone in the rear of the engine cylinders and a gate valve Il, pivoted at I8 may be moved between the full and dotted line-positions, respectively to close the scoop I0 and to close the opening I5. When the valve Il closes the scoop It, warm air enters the port I 6 and passes to the carburetor. Conversely, when the gate I1 closes the port I6, cold air enters the scoop I 0 and passes to the carburetor. The gate valvel I1 is moved by a piston-cylinder combination I9 and is so arranged that ,when fluid under pressure-is fed tothe cylinder, the valve Il closes the scoop I8 and when pressure is relaxed, fluid bleeds through an orifice 2i) in the piston. and is returned to the. engine through the pipe 2I, the piston moving the valve I1 to the port closing position by a spring 22.

In the adapter vI3 are bosses 23 and 24,l the former accommodating a temperature responsive yfluid valve 25 including an expansible diaphragm 26 contacted by the air stream passing through the adapter. Upon relative expansion and contraction of the diaphragmy 26, a plunger Since engine induction systems are 28 is moved to open and close a passage 2S between a pipe 30 and a pipe 3l, the latter being connected to the piston-cylinder unit l5. The degree of opening between the pipes 3@ and 3i will be governed by temperatures existing in the adapter I3. The pipe 35 is connected to a shut-oil valve 33, the latter in turn being connected by a pipe 33 to a source of uid under pressure such as the engine lubricating system, not shown. A plunger 35 operates in the housing ofthe valve 33 either to open orto close the valve to respectively establish or prevent uid 'passage from the pipe 35 to the temperature re-v The valve stern 35 is sponsive valve unit 25. extended to the right, as shown, to comprise an armature for a solenoid 3l, the right hand end of the stem 35, when the valve is open, striking a resilient leaf 38 to eiect closure'oi a switch comprised by the contact points 35l and 60. The contact point 39 is carried by the element 38, while the contact point t@ is mounted upon a cover plate 4I. The element 3B is connected to one end of the solenoid winding, said end likewise being connected to a terminal t2. 'I'he other end of the solenoid winding is connected to a terminal 43. It will be seen that the terminal 43 is connected through a circuit breaker 45 and a power source 66, to ground. The terminal 42 is connected to a terminal i5 of a diaphragm switch 59, the other terminal of said switch as shown, being grounded. This diaphragm switch 49 comprises an expansible diaphragm 50 carrying a switch point 5l 'which engages, under relative high pressure conditions within the diaphragm, with a fixed switch point 52 connected to the terminal t8. The interior of the diaphragm is vented through'a small aperture 53 and is connected by a tube 5d to a tube 56 mounted on the adapter boss 2t, the tube 5S having a small Venturi opening at its inner end 51 which is exposed to the air flow passing through the adapter.

'I'he operation of the apparatus is as follows:

We may assume that at the outset, ice conditions donot exist, and that the valve il is adjusted to cover port i6 permitting cold air iow into the carburetor. Under this condtion, the

opening 5l in the tube 56,will be clear and the low pressure from the venturi will be communicated to the diaphragm 53, separating the switch points 5I and 52, thus, the valve 33 will be closed and the temperature responsive valve 25 will be inactive and will have no control upon the valve I1. Now, if icing'conditions are encountered, ice will form on the end of the tube 56, closing the small opening 5l in same whereupon the low pressure or vacuum in the diaphragm 50 is relieved by air passing through the vent 53. 'I'he switch points 5| and 52 will contact to close the solenoid circuit through the terminal 42, the terminal 43, the normally closed circuit breaker 45, the power source 46, and

ground. With the solenoid energized, the valve stem 35 will move to an opening position permitting of fluid oW to the valve unit 25 as shown. Since low temperature conditions exist in the adapter I3, and since the unit 25 isinitial- 1y adjusted to maintain a temperature of approximately 35 F. In the adapter, the valve 25 Will be opened and will permit fluid flow to the piston-cylinder unit I9 to raise the gate valve I1 to the position shown in full lines.

`Revertinginow tothe solenoid valve 33, assoon as the stem 35 moves to the right, the contacts 39 and 40 are closedto short circuit the diaoil lilow through the valve and will consequently f adjust the valve l1 to a proper intermediate po,

sition whereat the 35 temperature is maintained in the adapter, by an admixture of cold and warm air respectively entering the scoop l5 and the port |55. 'Ihe warm air in the adapter i3) will have dissolved the ice from the tube it to open the contacts 5l, 52 but temperature control by virtue of the `valve continues since the valve unit 33 remains open to maintain the temperature at approximately 35 F. After a reasonable interval of time, a member of the aircraft crew may operate the circuit breaker i5 by which the solenoid is de-energized and the pressure fluid is cut-oir from the valve 25 and the piston-cylinder unit I9. This .will return the system to the full cold air condition with the valve il covering the port I6. If the icing condition in the atmosphere has ceased, the apparatus will stay in the cold air adjustment, but if the'icing condition still exists, ice will form on the tube 55 and the system will be readjusted for temperature control by the temperature responsive valve unit 25. Thus, the air craft crew may occasionally operate the circuit breaker i5 to return the system to the cold air adjustment but the system will automatically respond to ice conditions when such are encountered.

If desired, ,an ice indicator in the formv ci a light or the like may be connected in the circuit with the.diaphragm unit t9 to serve as a visual warning of the presence of ice.

It will be obvious to those skilled in the art that the several units 25, 5S, 33 and d3 may be consolidated into a single piece of apparatus or' may be rearranged in two or three pieces of apparatus to provide for greater compactness and to allow for integral electrical or hydraulic connections. However, it isdeemed that the functions of" the several devices as shown are necessary to accomplish the desired type of temperature regulation operative in response to icing conditions. -It is acknowledged that the diaphragm switch device 50 in conjunction with the tube 56 is a known combination of elements used for visual indication of icing conditions. Likewise, the temperature responsive vvalve 25 and the piston cylinder assembly i9 are known devices for the control of intake air temperature. However, the coordination of these units to provide for automatic temperature control only in response to icing conditions is believed to be new and this combination results in superior engine operation since, as indicated in the beginning of this description, fully cold intake air is desired at all times except when ice forming atmospheric conditions exist. The apparatus herein shown eliminates any need of attention on the part of the aircraft crew, being fully automatic in operation. Previously, a warning signal or light actuated by the tube 56 and the diaphragm switch 49 had to be interpreted by the aircraft crew who then have to take action as to proper control of temperature of air entering the engine, by the use of hydraulic or mechanical controls which are relatively complicated in their applicationl between crew quarters and power plants of multi-engine aircraft. The simple cutout circuit, the only selective control in this sysl 2,208,639 tem, is simple and crew can even neglect its n for long periodswithout harmful effects.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those vskilled in the art, after understanding my invention, that various changes and modleations may be made therein without departing from the spirit or scope'thereof. I aim in the appended claims to cover all such modications and changes.

What I claim is: f

1. In combination, in the intake system of an internal combustion engine, a valve adjustable to pass warm or coldrair to the engine intake, an icing responsive device including a circuit adapted to be closed upon ice formation in the intake, an intake temperature responsive means for controlling the position of said valve includ-- a valving device for pressure fluid, and a solenoid operated shut-off valve, the solenoid being in series in said icing responsive circuit, said shutoff valve controlling pressure fluid supply to said temperature controlling valving device, said solenoid circuit including contacts organized to short circuit -said icing responsive device after initial solenoid energization thereby.

3. In combination, in the intake system of an internal combustion engine. a valve adiustabl to pass warm or cold air to the engine intake, an icing responsive device including a circuit adapted to be closed upon i'ce formation inthe intake, an intake temperature responsive means for controlling the position of said valve including a valving device for pressure iluid, a soienoid operated shut-olf valve, theA solenoid being in series in said icing responsive circuit,

vsaid .shut-off valve controlling pressure fluid supply to said. temperature controlling valving device, said solenoid circuit including contacts organized to short circuit. said icingA responsive device after initial solenoid energization thereby,

and a manualcircuit breakenin said solenoid circuit. v

'4; In combination with an internal combustion engine intake system, an ice warning indicator includingl an electric circuit having therein a solenoid, a uid valve operated by4 saidsolenoid, hydraulic means for Varying the intake air tem- -perature operated by iluidpressure, and avuidsupply connection to saidv hydraulic means passing through said iluid valve.

5. In combination with an internal combustion. engine intake system, an element in the intake having` a normally clear opening subject to closure by and upon formation of ice on the element, a normally inactive intake air temperature regulator operative when active to control entering air `to a temperature above that at which ice may form inr the intake, means responsive to closure of said opening by ice for starting and thereafter perpetuating operation of the regulator,

such perpetuation taklngplace lregardless of the presence or absence of ice on the element, and a selective manual control device for stopping operation of the regulator.

w C. SULZMAN. 

